1. Field of the Invention
Embodiments of the invention generally relate to methods and apparatus for increasing circulation and/or adjusting the temperature of a human. Embodiments of the invention may be used, for example, to prevent deep vein thrombosis (DVT).
2. Description of the Related Art
Venous thromboembolic disease continues to cause significant morbidity and mortality. Hospitalization in ranges of 300,000 to 600,000 persons a year is due to venous thrombosis and pulmonary embolism (PE), originating from blood clots in the veins and some clots traveling to the lung. PE is estimated to be the third most common cause of death in the United States, resulting in as many as 50,000 to 200,000 deaths a year.
Following various types of surgical procedures, as well as trauma and neurological disorders, patients are prone to developing DVT and PE. Regardless of the original reasons for hospitalization, one in a hundred patients upon admission to hospitals nationwide dies of PE. Patients suffering from hip, tibial and knee fractures undergoing orthopedic surgery, spinal cord injury, or stroke are especially at high risk. Therefore, prevention of DVT and PE is clinically important.
Studies indicated that factors contributing to the development of DVT include reduction of blood flow, vascular stasis, increase vessel wall contact time, coagulation changes, blood vessel damage, and pooling of blood in the lower extremities. It is believed that slowing of the blood flow or blood return system from the legs may be a primary factor related to DVT with greatest effect during the intraoperative phase. Also of concern is the postoperative period. Even individuals immobilized during prolong travel on an airplane or automobile may be at risk. Generally, without mobility, return of the blood back to heart is slowed and the veins of an individual rely only on vasomotor tone and/or limited contraction of soft muscles to pump blood back to the heart. One study shows that travel trips as short as three to four hours can induce DVT and PE.
Current approaches to prophylaxis include anticoagulation therapy and mechanical compression to apply pressure on the muscles through pneumatic compression devices. Anticoagulation therapy requires blood thinning drugs to clear clots in the veins which must be taken several days in advance to be effective. In addition, these drugs carry the risk of bleeding complications. Pneumatic compression devices, which mechanically compress and directly apply positive message-type pressures to muscles in the calf and foot sequentially, are not comfortable, are difficult to use even in a hospital, and are too cumbersome for mobile patients or for use during prolonged travel. In addition, most of them are heavy weighted and there are no portable or user friendly devices.
Therefore, there remains a need for an apparatus and method to increase blood flow and/or regulate body temperature in a human which can be used in reducing clots in a human extremity and preventing deep vein thrombosis.